1. Field of the Invention
The present disclosure is directed to a semiconductor device and method of manufacturing the same. More particularly, the present disclosure is directed to a semiconductor device free from the stress of gate spacers and physical and chemical damage on silicide regions and method of manufacturing the same.
2. Description of the Related Art
As the density of semiconductor devices increases, it has becoming increasingly difficult to use conductive polycrystalline silicon to secure enough conductivity for semiconductor devices to operate in a stable condition. As a result, conductive parts, previously composed of conductive polycrystalline silicon, such as gate electrodes, source/drain regions, contacts or via plugs, and signal transfer lines, have been gradually replaced by metallic materials. However, it is challenging to make metal patterns as compared to polycrystalline silicon. Also, because a semiconductor substrate is not metal, if metal contacts the semiconductor substrate, voids are formed in the metal. This not only makes the structure unstable, but also increases resistance such that the structure cannot be used in a semiconductor device. Therefore, the pattern is not formed of pure metal, but of silicide and metal. After the pattern is formed of silicon, a silicide layer is formed by combining a silicon pattern with metal. However, the silicide layer can be damaged where the characteristics of the silicide layer deteriorate and the shape of the silicide layer changes. Especially, the damage and the transformation of the silicide pattern of the source/drain region have an impact on the deterioration of characteristics as compared to the damage and the transformation of other parts.
Also, a gate spacer is generally formed from the transistors (or gates) of a semiconductor device. A gate spacer typically is formed of materials having a high degree of density and solidity. Due to the increasing integration of semiconductor devices and the small geometry of patterns, the stress generated by a gate spacer is becoming a concern. The volume of a semiconductor device increases or decreases in a repeated fashion as it absorbs or generates heat during manufacturing. As a result, various types of stresses are generated depending on the differences of heat expansion coefficients of elements forming the semiconductor device. These stresses deteriorate the characteristics of the source/drain and channel region of the semiconductor devices. Such stresses have been considered unimportant since they had an insignificant impact on the characteristics of a semiconductor device, but the impact of theses stresses has become more significant. Consequently, there is a need for research and development avoiding or relieving the stress caused by a gate spacer. Research has been conducted on removing the gate spacer. If the gate spacer is removed, the silicide region, which is comparatively weak, can cause trouble.